1. Field of the Invention
Embodiments of the present invention generally relate to heating, ventilating, and air conditioning systems. More particularly, the invention relates to a method and mechanism to control flow through heating, ventilating, and air conditioning duct systems.
2. Description of the Related Art
The control of air flow in heating, cooling, and ventilation applications has become more complex as building and home automation and energy management options increase. Most current air handling systems rely on fixed regulation devices such as variable setting louvers associated with diffusers in register boxes or automated dampers within the distribution piping. To some degree dampers may be controlled by the air handling controllers used in commercial buildings; however, most residential systems use fixed dampers that are set once during system start-up and then never adjusted or changed. In both the commercial and residential application, changes to layout or use of the building that occur over the life of the structure typically alter the air balance that was originally created or programmed into automated controllers. It is typical that these original settings and control parameters are not often changed or up-dated and therein air flow balance, comfort, and energy management suffer as the building ages and the use changes.
In recent years, several products have entered the market place that offer a limited degree of flexibility to alter and improve both original configurations and to alter air balance based on building usage or configuration changes. For the most part, these devices are installed in crawl spaces, attics, or above drop ceilings. Not only is the retrofit installation costly, but often it is compromised because it is an aftermarket product or application that is not optimized with the original design of the air distribution system. While this retrofit market is growing and seems to offer value, it has limitations. These limitations can be many, but in general the most impacting are limits to the flexibility of the newly installed systems to adapt to short term changes desirable in air distribution systems.
For example, a conference room is typically not used daily, but must have sufficient air flow to handle its air flow needs when in use. Therefore a room of this nature will typically have excess air flow a large percent of the time. In the residential application, kitchens, dinning areas, and living rooms often have a large percent of the overall square footage of the home. However, these rooms are often used in rather fixed blocks of time, but are typically supplied with a fixed air flow whether the room is in use or not. At a minimum, this leads to excess energy consumption and often leads to human discomfort in either these rooms or other rooms where air flow may be defined by the peak needs of these larger rooms.
A key market entry and penetration driver is the ability of a product to integrate into the retrofit market without costly additions or modifications to the existing systems and at the same time be compatible with manufacturing of new system devices for both commercial and residential applications. In addition to being functional, any air control or blocking device should fit within the confines of existing air distribution boxes installed in ceilings, walls, and floors of existing residential and commercial structures. This restriction substantially limits the nature of devices used to allow the control of air flow.
In residential application, many different air distribution box sizes exist, some square, others rectangular, and even others round. However, in a general sense, these air distribution “boxes” are typically scaled and sized in relationship to the size or diameter of the air delivery duct associated with them. Therefore for a given air volume, it is possible to broadly understand the likely size and nature of the air distribution box. Often the box is insulated to limit condensation during cooling periods and improve overall energy efficiency. This feature helps define the corresponding box dimension of a given duct size and therefore the air flow.
Square air distribution boxes have become more popular in the last few years and tend to be less variable in size. While it is not possible to limit options, typically one would find 8, 10, and 12 inch square air distribution boxes. These boxes would be used across the full range of duct sizes ranging from 5 through 10 inches. Unlike the rectangular box configuration, it is not common to distort or flatten ducts used with square boxes.
Not only must one consider the box width and length in the plane of the wall or ceiling surface, one must also consider that the box has a depth projection into the wall or ceiling, nominally 2¾ to 3¼ inches.
One can clearly see the challenge in finding a universal means, configuration, and size for a device to effectively reduce or close off the air flow across such a wide range of possible air distribution boxes. While one could suggest the challenge is less problematic with new installations, this is really not the case as most builders and contractors design and build using personal preference and experience and therefore altering constructions habits to enhance compatibility is not a realistic goal.
In order to minimize the number of different sizes and designs of an air flow device, it is necessary to understand the relationship between air flow volumes and most likely box sizes. While a single device size to fit all configurations is not feasible, the novelty of the disclosed design greatly limits the number of different sizes and configurations needed. One can also envision the challenge of achieving full closure of large ducts in small boxes without unduly restricting the full open condition. Thus, the embodiments of the present invention are directed to methods and apparatus that seeks to overcome these limitations.